United States President Donald Trump on Friday (July 20) launched a fresh attack on American trading partners, saying the EU and China were manipulating their currencies as he took another swipe at the US central bank.

The remarks on Twitter early in the day followed a CNBC interview in which Trump said he was willing to hit all Chinese imported to the United States with tariffs.

The harsh comments took fresh aim at pillars of the international economic system and compounded Trump's break with long-established norms by again openly rebuking the Federal Reserve.

They also signalled an undiminished appetite for battle on multiple fronts after a week dominated by coverage of the fallout from his dealings with Russian President Vladimir Putin.

In a pair of tweets, Trump said China, the European Union and others had been "manipulating their currencies and interest rates lower" while the dollar gained in strength, eroding "our big competitive edge." He said the Fed's course of tightening monetary policy "now hurts all that we have done." Fed has raised the benchmark lending rates twice this year, after three increases in 2017, and two more rate hikes are expected this year as the central bank removes stimulus from the economy to keep a lid on inflation.

The chance that inflation might accelerate has increased after the massive tax cut Trump championed, which has raised the US debt and budget deficit.

"The US should be allowed to recapture what was lost due to illegal currency manipulation and BAD Trade Deals," Trump said on Twitter. "Debt coming due & we are raising rates - Really?"